Aminierende, reduktive Kupplung aromatischer Aldehyde mit Tris(dialkylamino)methylvanandium (IV) zu N , N , N ′, N ′‐Tetraaalkyl‐1,2‐diaryläthylendiaminen

Aminative Reductive Coupling of Aromatic Aldehydes to N , N , N ′, N ′‐Tetraalkyl‐1,2‐diarylethylenediamines, Induced by Tris(dialkylamino)methylvanadium (IV) In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p ‐methoxybenzaldehyde, 1‐naphthaldehyde, furan‐2‐carbaldehyde) and secondary amines are coupled to give N , N , N ′, N ′‐tetraalkyl‐1,2‐diarylethylenediamines 1–6 . The reagents are tris(dialkylamino)methylvanadium(IV) compounds ( cf. Eqn. 2 ). These are generated in situ either from isolable chlorotris(dialkylamino) vanadium(IV) ( Eqn. 3 ), or preferably, from an Et 2 O/pentane solution of VCl 4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and 0.8 equiv. of an aromatic aldehyde, to give the products 1–6 in a one‐pot preparation ( Scheme 2 ). The yields range from 14 to 54%. The diastereoisomeric mixtures ( meso ‐ and (±)‐forms) obtained are separated by chromatography (Al 2 O 3 , petroleum ether/Et 2 O/Et 3 N), and the pure stereoisomers fully characterized. A mechanism of the reductive coupling induced by CH 3 V (NR 2 ) 3 is proposed ( Scheme 1 ).